Where findings of fact are filed by the trial court they shall form the basis of the judgment upon all grounds of recovery and of defense embraced therein. The judgment may not be supported upon appeal by a presumption of finding upon any ground of recovery or defense, no element of which has been found by the trial court; but omitted unrequested elements, where supported by evidence, will be supplied by presumption in support of the judgment. Refusal of the court to make a finding requested shall be reviewable on appeal.